Help needed!

[Feng Peirong]

Hi,

Thanks for your detailed information. And I don't know that only
2 of 3 connectors can be used at the same time. Thanks a lot.

Now I've already removed the internal 68 pin cable and the hard 
disk ST318436LW, only remain the ST34501N over the 50 pin cable 
with TE and TP on. The other end of the cable is the 50 pin -> 
68 pin external port, which is connected with a Yamaha CRW4260 
CD-R writer with terminated switch ON. The problem remains!

After disconnecting the external Yamaha CRW4260 and reboot, the
problem still remains!!

What else should I check? Where is the "Control High Term" switch?

-Peirong

Edmond Shwayri wrote:
> 
> On a "single-ended" SCSI bus you need to terminate both ends of the bus.
> In your case one end of the bus is supposed to be the 68 pin device while
> the other end is the 50 pin device.  Both these devices need to have their
> termination enabled and preferably both should have term power enabled.
> When one has a 68 pin device on one end and a 50 pin on the other end, you
> also must enable "high" termination on the SCSI controler.  The reason for
> this that while the "low" byte extends all the way from the wide device to
> the narrow device (and thus can be terminated by both devices), the "high"
> order byte starts at the wide and ends at the controler.  Therefore, the
> correct termination should be :
> 
> Wide 68 pin device : Term ON, Term Power ON.
> Narrow 50 pin device : Term ON, Term Power ON.
> Controler : High Term.
> 
> Looking at the specs for your wide drive, it looks like you will need to
> purchase an in-line terminator or use a wide cable which has a terminator
> at the end.  The drive can supply term power and should be told to do so.
> 
> If you still have problems, there is a jumper on the wide drive that
> can force the drive into SE (single-ended mode) which is what it should be
> auto-negotiating; however, maybe it isn't.
> 
> If you still have problems, try other cables.
> 
> Also, I am sure you realize this, but I will mention it anyway.  On
> Adaptec cards like the 2940UW, there are three ports : A 68 wide internal
> connector, A 50 pin narrow connector, and an external 68 pin wide
> connector.  Only 2 of the three can be used at a time (The SCSI bus must
> have two ends).  Therefore on a controler like that if you were to connect
> a 68 pin internal device and a 50 pin internal device, you should NOT
> connect anything to the external port.  In a case where you need to have
> internal wide and narrows AND use the external port, you would get a 68 to
> 50 pin converter and use that to connect the narrow device to the same
> cable as the wide device.
> 
> If you are sure all of this is right, then your problem could be caused by
> many other things (interrupt conflicts, bug in the driver, etc...)
> 
> On Mon, 3 Jul 2000, Feng Peirong wrote:
> 
> > Hi,
> >
> > > check your termination.
> > > check your cable.
> >
> > Ya, the ST318436LW is connected without terminator and no jumper
> > indicates
> > terminator, I remove this disk temporarily. But the ST34501N has a
> > jumper
> > indicates the terminator, so I keep it. The two disks were connected
> > using
> > two individual cable, one 68pin and one a little wider 50pin cable.
> >
> > But after removing the one without terminator ST318436LW, I copy a
> > redhat
> > ISO to sda1 and compute md5sum again. The problem remains.
> > 
> > > what is your mother board ?
> >
> > The mother board is P6LXI.
> >
> > Need other information?
> >
> > Peirong
> >
> >
> > To Unsubscribe: send mail to majordomo at FreeBSD.org
> > with "unsubscribe aic7xxx" in the body of the message
> >


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